Oxford hollow

A particular form of the HOLLOW consisting of
a simple flat paper tube which is glued to the
spine of the text block on one side, and to the
inside of the spine of the covers, leaving a
hollow opening between. The term presumably
derives from the fact that Oxford binders were the
first to use it, namely for leather-bound Bibles.
It is actually a ONE
ON AND ONE OFF hollow. (140 )